Split torque drivetrain for multiple wheel vehicle

ABSTRACT

A split torque gearing arrangement for use in a multiple wheel vehicle comprising four bevel torque delivery gears, one of which serves as a torque input gear, each of the other bevel gears serving as output gears, said gears including an internal clutch structure for selectively establishing a driving connection between the input gear and one of the output gears while the other two output gears are inactive and for clutching the input shaft to each of the output gears for split torque delivery, spaced bearing means for journalling the output gears and for accommodating gear tooth reaction torque and means for adjusting the bearing means to establish proper clearances between meshing gear teeth and for maintaining a desired preload on the bearing elements.

United States Patent [1 1 Adams SPLIT TORQUE DRIVETRAIN FOR MULTIPLEWHEEL VEHICLE Oct. 30, 1973 Primary Examiner-Leo Friaglia AssistantExaminer-Randall A. Schrecengost Attorney-Keith L. Zerschling et al.

[57] ABSTRACT A split torque gearing arrangement for use in a multiplewheel vehicle comprising four bevel torque delivery gears, one of whichserves as a torque input gear, each of the other bevel gears serving asoutput gears, said gears including an internal clutch structure forselectively establishing a driving connection between the input gear andone of the output gears while the other two output gears are inactiveand for clutching the input shaft to each of the output gears for splittorque delivery, spaced bearing means for joumalling the output gearsand for accommodating gear tooth reaction torque and means for adjustingthe bearing means to establish proper clearances between meshing gearteeth and for maintaining a desired preload on the bearing elements.

3 Claims, 2 Drawing Figures Patented Oct. 30, 1973 2 Sheets-Sheet 'lPatented Oct. 30, 1973 3,768,821

2 Sheets-Sheet 2 SPLIT TORQUE DRIVETRAIN FOR MULTIPLE WHEEL VEHICLEGENERAL DESCRIPTION OF THE INVENTION My invention is adapted especiallyto be used in split torque delivery drivelines for heavy vehicles havingmultiple traction axles. One heavy vehicle driveline capable ofembodying the improvements of my invention includes a pair of rearwardtraction wheels, a pair ofintermediate traction wheels and a pair offront wheels which may be used under some driving conditions as drivingwheels but which function primarily as dirigible road wheels foraccomplishing turning maneuvers. The engine in the disclosed vehicledriveline is mounted rearwardly over the rear traction wheels.

A multiple speed ratio transmission connects drivably the torque outputshaft of the engine, which may be a diesel engine, to the input torqueelement of a right angle drive mechanism. Torque is deliveredtransversely of the principal vehicle axis to either intermediatetraction wheel through a right angle drive mechanism. An intermediatetraction wheel is connected to an output gear element of my improvedsplit torque gearing, and the input element thereof is connected to anoutput shaft of the right angle drive gearing. A second output gearelement of my split torque gearing is connected through a driveshaft anduniversal joint arrangement to one of the rear traction wheels. Acompanion split torque gearing mechanism of my invention is mounted onthe opposite side of the right angle drive gearing for receiving thebalance of the driving power delivered by the multiple ratiotransmission. A first output element of the second split torque gearingarrangement is connected to the other intermediate traction wheel and asecond output element thereof is connected to the other rear tractionwheel.

Each of the front wheels is adapted to be connected to the third outputgear of a separate one of the split torque gearing mechanisms.

When the clutch mechanism is disengaged, torque delivery to the rearwheels and the intermediate wheels is interrupted. When the clutchmechanism is applied, torque is delivered to each of the output gearelements.

Vehicle propelling rnud screws are situated on opposed sides of thevehicle and extend longitudinally for rotation about axes that areparallel to the direction of motion of the vehicle. Each mud screw isconnected to the third output gear element on the separate one of thesplit torque gearing arrangements of my invention. A torque transferdrive chain is used for establishing the driving connections betweendried screws and the third output gear elements. Such chain drives maybe actuated and deactivated by driver operating control mechanisms. Whenthe vehicle propelling mud screws are active, the clutch structure whichforms a part of my improved split torque gearing arrangement isdisengaged thereby interrupting torque delivery to the rear wheels andthe intermediate wheel so that a greater proportion of the enginehorsepower will be delivered to the mud screws for vehicle purposes. Thevalves from the torque which is delivered to the front wheels maintainsrotation of the front wheels so that the rolling velocity of the frontwheels corresponds to the linear velocity component of the mud screw.The rotation of the front wheels during operation of the mud screwsmakes it possible to maintain directional control of the vehicle.

The bevel gear elements of the split torque gearing arrangement of myinvention are journalled within a stationary housing by a four-pointtapered roller bearing arrangement. The bearings may be adjusted andpreloaded to maintain a proper meshing relationship between theindividual gear element and for maintaining a desired bearing preload.The bearing arrangement is capable also of establishing a reactiontorque for compensating for unbalanced gear loads.

BRIEF DESCRIPTION OF THE FIGURES OF THE DRAWINGS FIG. 1 shows inisometric form the vehicle driveline components for a heavy dutymultiple purpose yehicle capable of both road and off the roadoperation.

FIG. 2 is a split torque gearing arrangement capable of being used inthe driveline of FIG. 1.

PARTICULAR DESCRIPTION OF THE INVEN- TION In FIG. 1 reference character10 designates one end ofa diesel engine shaft connected to a torqueinput element of a torque transfer gear case 12 by means of a doubleuniversal joint 14. The output element of the torque transfer gear case12 is connected to a torque input shaft of a multiple ratio powertransmission mechanism 16. Preferably the transmission mechanism 16 iscapable of. providing either four or five forward driving speed ratioson either one reverse ratio or two reverse ratios. The power outputshaft for the transmission mechanism 16 is connected to the torque inputelement of a right angle drive transmission 18, a double universal joint20 being provided for this purpose.

The right angle drive 18 has two output shafts, one extending in eachaxial direction with respect to the direction of motion of the vehicle.The direction of motion is indicated by the directional arrow 22. Eachoutput shaft is connected to theinput gear element of a split torquegearing arrangement embodying the improvements of my invention. Onegearing arrangement is indicated by reference character 24 and the otheris indicated by reference character 26. One output gear element of thesplit torque gearing arrangement 24 is connected to a universal jointshown in part at 28 which in turn delivers torque through a driveshaftto an intermediate traction wheel. The output element for the gearingarrangement 26 is connected to the universal joint shown in part at 30,which in turn is coupled through a driveshaft to the other intermediatedrive wheel. A second torque output gear element of the gearingarrangement 24 is connected through universal joint 32 and driveshaft 34to rear traction wheel 36. The connection between the rear tractionwheel and the adjacent end of the driveshaft 34 is effected by a rightangle drive 38 and another universal joint 40. The corresponding torquedelivery path for the opposite rear traction wheel 42 is defined byright angle drive 44, universal joint 46, driveshaft 48 and universaljoint 50, the latter being connected drivably to an output element ofthe split torque gearing arrangement 26.

A third output element of the gearing arrangement 24 is connected todriveshaft 52. A selectively engageable synchronizer clutch located at54 is adapted to establish a driving connection between shaft 52 and thedrive sprocket 56. The torque delivery path between clutch 54 andsprocket 56 is effected by a chain drive located at 58.

nection betweeen drive chain 64 and the third output gear element ofgearing arrangement 26.

Driveshaft 68 is connected drivably to the remaining output gear elementof the gearing arrangment 26. Each driveshaft 52 and 68 is connected toa separate one of the front road wheels as shown at 70 and 72respectively. If desired, an overrunning clutch may be exposed betweenthe shaft 52 and the road wheel 70 and between the driveshaft 68 and theroad wheel 72. These clutches are shown at 74 and 76, respectively.

During normal over-the-road operation of the vehicle, the rollingdiameter of the front and intermediate driving wheels may be madeslightly larger than the rolling diameter of the rear road wheel. Thiscan be done by reducing the air pressure in the pneumatic tires for thefront and intermediate road wheels relative to the pneumatic pressure inthe driving traction wheels at the rear of the vehicle. In thesecircumstances the overrunning clutches 74 and 76 will overrun and notorque will be delivered through the driveshafts 52 and 68. All of theunused torque then will be delivered to the rear traction wheels. If theoverrunning clutches 74 and 76 are not used, driving torque is deliveredat all times to the forward wheels.

If the vehicle is operated off-the-road in swampy territory or in mud,it is possible that the weight of the vehicle will prevent normal roadtraction. In these circumstances the drive screws 60 and 62 may beactuated by engaging the clutches shown at 54 and 66. Driving torque ofthe engine then is delivered to the drive screws in order to provideadequate torque delivery to the drive screws. It is desirable, but notnecessary, to disengage the intermediate and rear wheels. This isaccomplished by disengaging the clutch mechanism which forms a part ofthe gearing arrangements 24 and 26.

I have shown in FIG. 2, in generally schematic form, the principalcomponents of gearing arrangment 24. The gearing arrangement 26 isidentical to the gearing arrangement 24, and for this reason only thelatter will be described.

The input shaft 78 for the gearing arrangement 24 is journalled by meansof tapered roller bearings 80 within bearing opening 82 formed in thestationary housing 84. The housing 84 encloses the gearing elements ofthe gearing arrangement 24, and it is provided with a second bearingopening 86. A first bevel ring gear 88 is secured to hub 90, which isjoined to or formed integrally with the input shaft 78.

A second bevel gear is connected to gear hub 94 which in turn is joinedto or formed integrally with sleeve shaft 96. Sleeve shaft 86 isjournalled by means of tapered roller bearing 98 within the bearingopening 86.

A shaft extension 100 carried by the hub 90* extends within sleeve 96.Sleeve 96 is journalled on the extension 100 by spaced tapered rollerbearings 102 and 104. External spline clutch teeth 106 are formed on theouter periphery of the sleeve 96 at one end thereof. These are alignedwith external clutch teeth 108 formed on the hub 90. Clutch sleeve 110,having internal teeth, mesh with teeth 106. Sleeve 110 may be shifted ina right hand direction as viewed in FIG. 2 so that its internal teethdrivably engage teeth [08 thereby establishing a positive drivingconnection between shaft 78 and output shaft 112, through the sleeve 96.Shaft 112 is connected to one intermedaite traction wheel throughuniversal joint 28.

Inner race for bearing 104 engages shoulder 114 formed on the hub 90.The inner race for the bearing 102 engages adjusting nut 116, which isthreaded on the end of shaft 100. The outer race for bearing 102 isengaged by externally threaded adjusting nut 118, which is receivedwithin internal threads formed in the sleeve 96.

A spacer sleeve is disposed between the outer race for bearing 102 andthe outer race for bearing 104.

Output gear 122, which serves as a torque input element for synchronizerclutch 54, is a bevel pinion which engages drivably the ring gear 88. Itis journalled for rotation about the axis of shaft 124 within thehousing 84. Gear 122 meshes with gear 88 but it is not engaged with gear92.

Output gear 126, which is in the form of a bevel pinion, is connecteddrivably to driveshaft 34 through the universaljoint 32. It meshes withgear 92 but it does not mesh with gear 88. It is adapted for rotationabout the axis of the shaft 128 and is journalled within the housing 84.The axis of shaft 128 is displaced with respect to the axis of shaft 124as indicated in FIG. 2.

The four-point spaced bearing arrangement of my improved split torquegear system adapts the gear system for high torque delivery with minimumdeflections at the bearing points. When the clutch 110 is engaged, norelative motion occurs at the spaced roller bearings 104 and 102. Thesebearings, however, act at this time to accommodate the reaction torquecouple that is introduced by reason of the gear tooth loading on theoutput gear 122 and 126. When the clutch 1 10 is disengaged, relativemotion occurs between sleeve 96 and shaft extension 100, but thebearings still are capable of acting as spaced bearing points forresisting unbalanced force couples due to the gear tooth loading.

During assembly the ring gears 92 and 88 are mounted within the housing84 and the spaced tapered roller bearings 98 and 80 are loaded by theirrespective adjusting nuts 129 and 130. The nuts 129 and 130 are adjusteduntil the bearings are snug. The externally threaded adjusting nut 118then is adjusted together with the appropriate readjustment of nut 82until the proper clearance exists at the mesh between the gear 122 andgear 88. After this adjustment is accomplished, gear 92 is adjustedrelative to gear 126 by backing off 'nut 118 and appropriatelyreadjusting nut 129. This final adjustment does not affect the meshingengagement between gears 122 and 88. Thus, each gear can beindependently adjusted without affecting the adjustment of the other.After both adjustments are completed, adjusting nut 1 16 is tightenedthereby establishing the proper preload on the bearings 102 and 104.

Having thus described the preferred form of my invention, what I claimand desire 'to secure by US. Letters Patent is:

l. A vehicle driveline having an engine, a power transmission mechanismand a right angle cross drive adapted to receive power from saidtransmission mechanism and to distribute to each of two transverselydisposed shafts, a split torque delivery gearing arrangement comprisingan input member connected to an output element of said cross drive, ahousing having spaced coaxially arranged bearing openings, a firstoutput shaft journalled in one bearing opening, an input shaftjournalled in the other bearing opening, a first ring gear carried bysaid input shaft, a second ring gear drivably connected to said outputshaft, a second output shaft and a third output shaft mounted forrotation about an axis transverse to the common axis of said firstoutput shaft and said input shaft, said second and third output shaftsbeing offset, one with respect to the other, second and third outputgears connected to said second and third output shafts, respectively, ahub sleeve connected to said second ring gear and extendingconcentrically with respect to portions of said input shaft, spacedbearings disposed between said input shaft extension and said hubsleeve, a clutch hub connected to said first ring gear, clutch teethformed on said sleeve in registry with said clutch hub, a clutch elementadjustable in one direction or the other to establish a drivingconnection between said clutch hub and said sleeve when it is moved toone axial position and to disengage such connection when it is moved inthe opposite axial direction, a vehicle propelling drive screw mountedon either transverse side of the vehicle, a torque transfer drivemechanism connecting drivably the second output shaft to one of saiddrive screws, disengageable clutch means for interrupting the drivingconnection between said second output shaft and the drive screw, and atorque delivery driveline between forward road wheels and said secondoutput shaft, the first and third output shafts respectively beingconnected drivably to intermediate and rear vehicle traction wheels.

2. The combination as set forth in claim 1 wherein the spaced bearingsfor said input shaft extension in said sleeve comprises tapered rollerbearings each having an inner race and an outer race, a sleeveinterposed between said outer bearing races, the inner bearing race ofone roller bearing engaging the hub of said first ring gear, anadjusting nut carried by said input shaft extension and engaging theinner race of the other roller bearing, a second adjusting nutthreadably connected to said sleeve and engaging the outer bearing racefor said second roller bearing whereby the operating clearances may beestablished at the meshing engagement of said first ring gear and saidfirst output shaft.

3. The combination as set forth in claim 2 wherein the bearing forjournalling rotatably the input shaft with respect to said housing is athird tapered roller bearing with an inner race and an outer race, thebearing for journalling said sleeve with respect to said housingcomprising a fourth tapered roller bearing with an inner race and withan outer race, and adjusting nuts threadably connected to said housingand engageable with the outer races of said third and fourth rollerbearings.

1. A vehicle driveline having an engine, a power transmission mechanism and a right angle cross drive adapted to receive power from said transmission mechanism and to distribute to each of two transversely disposed shafts, a split torque delivery gearing arrangement comprising an input member connected to an output element of said cross drive, a housing having spaced coaxially arranged bearing openings, a first output shaft journalled in one bearing opening, an input shaft journalled in the other bearing opening, a first ring gear carried by said input shaft, a second ring gear drivably connected to said output shaft, a second output shaft and a third output shaft mounted for rotation about an axis transverse to the common axis of said first output shaft and said input shaft, said second and third output shafts being offset, one with respect to the other, second and third output gears connected to said second and third output shafts, respectively, a hub sleeve connected to said second ring gear and extending concentrically with respect to portions of said input shaft, spaced bearings disposed between said input shaft extension and said hub sleeve, a clutch hub connected to said first ring gear, clutch teeth formed on said sleeve In registry with said clutch hub, a clutch element adjustable in one direction or the other to establish a driving connection between said clutch hub and said sleeve when it is moved to one axial position and to disengage such connection when it is moved in the opposite axial direction, a vehicle propelling drive screw mounted on either transverse side of the vehicle, a torque transfer drive mechanism connecting drivably the second output shaft to one of said drive screws, disengageable clutch means for interrupting the driving connection between said second output shaft and the drive screw, and a torque delivery driveline between forward road wheels and said second output shaft, the first and third output shafts respectively being connected drivably to intermediate and rear vehicle traction wheels.
 2. The combination as set forth in claim 1 wherein the spaced bearings for said input shaft extension in said sleeve comprises tapered roller bearings each having an inner race and an outer race, a sleeve interposed between said outer bearing races, the inner bearing race of one roller bearing engaging the hub of said first ring gear, an adjusting nut carried by said input shaft extension and engaging the inner race of the other roller bearing, a second adjusting nut threadably connected to said sleeve and engaging the outer bearing race for said second roller bearing whereby the operating clearances may be established at the meshing engagement of said first ring gear and said first output shaft.
 3. The combination as set forth in claim 2 wherein the bearing for journalling rotatably the input shaft with respect to said housing is a third tapered roller bearing with an inner race and an outer race, the bearing for journalling said sleeve with respect to said housing comprising a fourth tapered roller bearing with an inner race and with an outer race, and adjusting nuts threadably connected to said housing and engageable with the outer races of said third and fourth roller bearings. 